An 82-year-old man was referred to our hospital because of bilateral leg swelling and ecchymosis. A hemostatic study showed prolonged aPTT, <1% factor VIII coagulant activity, and a high titer (30.4 Bethesda Units/ml) of factor VIII inhibitor. The diagnosis of acquired hemophilia A (AHA) was made, and treatment with prednisolone (PSL) was started. Within one month of treatment, the hemorrhagic symptom disappeared, aPTT levels returned to normal, and his factor VIII inhibitor was eradicated; however, factor VIII inhibitor was detected again when PSL was decreased to 10 mg/day. We then added cyclosporine A (CyA) to PSL as a second line salvage therapy. CyA therapy resulted in the resolution of AHA with marked and prolonged efficacy; however, hot, red tumors appeared in his right arm and left thigh. Needle aspiration of the tumors revealed muscle abscess, and Nocardia brasiliensis was isolated. We started treatment with sulfamethoxazole-trimethoprim, and the abscess healed promptly without recurrence.